This study is designed to assess the levels of drug exposure following treatment with tislelizumab administered as a subcutaneous (SC) injection compared to intravenous infusion (IV) as first-line therapy in adults with gastric or gastroesophageal junction (GEJ) that is locally advanced and cannot be surgically removed or has spread from the stomach to other areas of the body. Approximately 351 patients will be participating in this study. The study is composed of a screening period, a treatment period, and a follow-up period.
Histologically confirmed, locally advanced unresectable or metastatic gastric/ gastroesophageal junction (GEJ) adenocarcinoma.
No previous systemic therapy for locally advanced unresectable or metastatic gastric/GEJ cancer.
At least 1 measurable or nonmeasurable lesion per RECIST v1.1 as determined by investigator assessment.
Must be able to provide tumor tissues for biomarker assessment.
Squamous cell or undifferentiated or other histological type gastric cancer (GC)
Active leptomeningeal disease or uncontrolled brain metastasis. Patients with equivocal findings or with confirmed brain metastases are eligible for enrollment provided that they are asymptomatic and radiologically stable without the need for corticosteroid treatment for ≥ 4 weeks before randomization.
Diagnosis with gastric or GEJ adenocarcinoma with positive human epidermal growth factor receptor 2 (HER2).
Active autoimmune diseases or history of autoimmune diseases that may relapse.